I am sorry to hear you are worried about Zoey. My name is***** am a veterinarian and will do my best to help.
It sounds like she is hurting somewhere, either internally (stomach, intestines), her spine (neck or back), or sometimes dogs do this when the anal glands are impacted or infected. Is she eating normally? If not it is probably not her stomach.
If it is her anal glands, they need to be emptied, and if they are infected, she might need antibiotics. This is best done by someone experienced at finding and checking these glands like a veterinarian, vet tech, or groomer.
If it is her back or neck, baby aspirin might help. How much does she weigh? You can give a baby or low dose aspirin (81 mg) to a 15 to 20 pound dog. If she is smaller, give 1/4th to 1/2. Give it with food and if she vomits do not give it again. Do not give Aleve, Advil (ibuprofen), or any other over the counter pain medication except aspirin. Your veterinarian will have safer and more effective pain medications than aspirin, but in a pinch aspirin is OK in most dogs.
Here is a video of expressing anal glands:
But my best recommendation would be a visit to your veterinarian. Let me know what else I can answer or help with. Rebecca